Increased flexibility in telephone call services has expanded greatly the options available to telephone users. Many options are now available to allow users to call locations throughout the world, access special focus services, and customize personal telephone services.
Traditionally, costs of telephone service were limited to a fee for monthly usage and additional fees for long-distance calls. In such a system, the risk of additional costs due to unauthorized telephone usage was not significant.
Now, services provided through the telephone increased dramatically the cost problems associated with telephone usage and ownership. Expensive and sometimes objectionable services, information and purchasing programs are now readily available to anyone with a telephone.
For example, telephone services often charging several dollars per minute are accessible through most home telephones. An unauthorized user can utilize these services through another person's telephone, placing the liability on the owner. The situation becomes even more problematic when enticing advertisements touting these services induce children to call. The costs of these products and services may not be identified to the actual user of the telephone, but rather are directed toward the owner of the telephone.
Costs associated with the unauthorized use of telephones has thus become a significant risk consideration for any telephone owner. Considerable time and expense has been devoted to addressing this problem. The most prevalent and promising approach has been to limit in some way the calls that can made from one's telephones.
A typical situation involves a business operator who prohibits telephone use by customers. The risk of unauthorized costs is thus avoided at the cost of inconvenience to customers. Additionally,
the operator may not always be present to prevent a customer or interloper from furtively incurring charges.
More elaborate schemes for avoiding additional costs include a centralized business telephone system through which all calls are routed. A complex computer control system requiring user authorization and billing codes is often included in relatively large office systems. Such a system is expensive and well beyond the reasonable scope of an individual telephone owner or small business operator.
In an attempt to reduce the cost and complexity of controlling access to telephone services and numbers, attempts have been made to develop devices to prevent undesirable telephone operation. Cost, complexity, limited flexibility, limited applicability and ease of circumvention have prevented these from significant success.
One device sold on the open market under the name TC-1013SL, Programmable Call Controller, by Tel Control, Inc., is available. This device is placed serially between the telephone wall outlet and the operative telephone. While this device provides an improvement over previous technologies, it suffers from many limitations.
The in-line TC-1013SL package is visually obvious, allowing even an unsophisticated user to circumvent the call restriction device. To prevent circumvention, a simple plastic cover containing slots through which the telephone cable connectors will not easily pass is placed on the device. To remove the call restrictor, a user need only force the package open or force the cables through the slots and connect the phone directly to the telephone line. The user can then place calls without restriction.
A further constraint of the device is the need for a complex multilevel protocol to program it. Programming by a user requires several levels of steps, each dependent upon the previous steps. The complexity of its operation limits its adaptability, increases the probability of errant programming, and intimidates the typical prospective purchaser.
A further problem arises from the complexity of programming inherent in previous devices. When a user picks up the telephone to make a call or begin programming, a connection is recognized by the local telephone company. A dial tone is transmitted by the local telephone network to the user's telephone and a timer is begun. Upon recognition of the first digit by the local telephone company, the dial tone is interrupted; but, the sensing of phone numbers dialed continues. As the device is programmed, the circuits at the phone company wait for a call to be placed. A predetermined time after the initiation of the original dial tone, a telephone company monitoring circuit judges that an unsuccessful attempt has been made to make a telephone call. Typically, an audible error message is then generated on the line telling the user to hang up and retry the call. Additionally, access to the local telephone network is discontinued.
Consequences of the excessive connect time can be significant. For example, a user may be led to believe that the attempt to program the device has been unsuccessful and may terminate the attempt. Additionally, while the timer is running, a portion of the local telephone network is dedicated to the call, occupying the limited available resources at the phone company. While this may not be significant in an individual case, the cumulative effect of many devices would place a substantial burden on the local network.
There also exists a possibility that the sequence of numbers entered by the user may be interpreted by the telephone network as a recognizable number. An unintended number is thus dialed and the line is connected to another customer during programming. The probability of this occurrence may be reduced by choosing a programming sequence that differs substantially from typical recognizable telephone codes. However, where the user inaccurately enters the programming numbers, an accidental connection may be established.